A technique of simultaneously projecting with a plurality of projectors arranged side by side is known. In that case, the plurality of projectors needs to be linked by being connected to each other via a network or the like. As a technique of linking a plurality of projectors, the technique of PTL 1 is known. PTL 1 discloses that, in order to make driving conditions uniform among a plurality of projectors, one projector projects a code (for example, a QR code (trademark registered)) including a driving condition using infrared rays whereas the other projector (s) picks up an image of the code, acquires the driving condition and reflects this on its/their own driving condition.